Rectifying device



July 5, 1932. P. R. COURSEY ET AL RECTIFYING DEVICE Filed July 5, 1928 HIVENTORS Philip Ru Cour'mzy B Humfrey Finch-ewe FJTTOENEY Patented July 5, 1932 UNITED STATES PATENT OFFICE PHILIP RAY QOURSEY, OI RICHMOND, AND HUMFREY ANDREWES, OF LONDON, ENG- LAND, ASSIGNORS'TO'DUBILIER CONDENSER CORPORATION, OF YORK, N. Y., A

CORPORATION OF DELAWARE nncrrmrme nnvion vApplication filed July 5, 1928, SeriaLNo. 290,392, and in Great Britain July 7, 1927.

This invention relates to an improvement in rectifying devices employing thermionic tubes and adapted to receive varying, inter mittent, or alternatin current and to supply a modified or rectifie current to a work circuit.

An object of this invention is to provide means for improving the efiiciency of rectifying devices by eliminating losses such as those present in transforming devices.

Another object of this invention is to supply the filament current and anode potential of thermionic tubes from an intermittent or an alternating current source of supply, modifying the values of such current by means of a capacitive unit without the necessity of using transforming devices.

An additional object of this invention is to lower the cost of making the devices disclosed by the substitution of a condenser for a transformer.

A further object of this invention is to provide an additional impedence means in circuit with a capacitive unit in a rectifying device to limit or prevent surges in such device.

In one embodiment of this invention the same hasbeen applied to rectifying units such as those used in battery eliminators and, for

i a better understanding of this invention, reference is made to the accompanying drawing in which like reference numerals indicate the corresponding parts:

Fig. 1 of the drawing discloses a circuit employing certain features of this invention,

and 7 Figs. 2 and 3 disclose modifications employing additional novel features.

In rectifying devices which are suitable for q use in so-called battery eliminators or devices for supplying suitable energy to radio sets from alternating current supply mains, it is customary to employ either a double or a single wave thermionic rectifying valve supplied with the necessary filament current and anode potential from a small transformer.

It is well known, however, that with the small transformers used in such eliminators or devices, owing to the large ratio of the magnetizing current to the full load current and to other factors, the efficiency of such transformersis usually low. As the actual power in watts required for energizing such a device may not be more than approximately 10 watts and, as such an arrangement using a transformer may require 100 or more watts, an improvement in the efliciency is highly desirable.

Referring to Fig. 1 of the drawing, an alternating current source of supply is shown impressed upon the mains 1 and2 of a-rectifying device embodying the principles of this invention. A conventional thermionic rectifying valve V is shown having a plate P and filament F. The filament F is connected across the mains 1, 2 and receives its energy therefrom. A condenser C is inserted in series with the filament F, the impedance of the condenser serving to supply the necessary current to the filament F of'the rectifying valve. While only one filament is shown it is obvious that a plurality of filaments,'such as are commonly used in a double wave rectifying valve, may be employed. It is also evident that any desired means for further regulating the current flowing through the filament may also be used. It will also be recognized that a thermionic tube having three or more elements and employ inga grid as indicated in Fig. 1 maybe used in place of the two-element valve shown, and thatthis invention may be used to supply energy to the various thermionic tubesin any radio circuit in general as well as to the rectifying circuitshown. The capacity of the condenser G will have a fairly large value with the usual type of rectifying valve, as the filament current required may be of the order of 0.5 amperes. The power factor angle, however, of such condenser will be quite small and the losses in the same will be negligible. Therefore, the power consumed will be only that required to heat thegfilament.

The arrangement shown inFig. 1 is particularly adapted for use with" a relatively high voltage supply source and no transformer for the anode potential of the recti fying valve is necessary. Hence, aunit comprising a rectifying valve V andjacondenser C" is all that is requiredto supply rectified current for the anode potential of a radio set. In practice, however, a condenser such as C is bridged across conductors 3 and 42 to smooth out the rectified current obtained.

The circuit shown in Fig. 2 is particularly adapted for use with a source of alternating current supply of lower potential. In this case the condenser G must be relatively larger, but the rectifying valve anode potential is raised by means of a small auto transformer having windings as indicated at L and L". Such auto transformer may be made very small as it has to supply .only the rectified direct current energy which, with the usual type of radio'receiver, amounts to only one or two watts, hence the efliciency of the unit may be kept quite high.

Fig. 3 shows another feature of this invention which comprises the insertion of an additional impedance element in series with the condenser G for the purpose of limiting current surges due to the charging of the condenser when switching the same intoor out of circuit. Preferably, this impedance is made inductive since its current limiting characteristics are then opposite to that of the condenser. The value of the impedance may be relatively small. Such an impedance element may, of course, be used to advantage in the circuits shown in Fig. 2.

For the purposes of illustration, this invention has been shown and described as applied to a rectifying device but, as many other and varied forms and uses will present themselves to those versed in the art without departing from the spirit of this invention, we do not wish to be limited either in structure or arrangement except as indicated by the terms and scope of the appendedclaims.

We claimi' 1. In an electrical circuit containing a thermionic tube, a source of supply energy impressed upon the circuit, a filament of the tube connected to said source of supply, a condenser in series with the filament circuit, and an impedance in circuit with said condenser.

2. An electrical circuit containing a thermionic tube, a filament ofsaid tube connected to a source of energy, a condenser in series with the said filament circuit and a'choke coil in series with the condenser and adapted to reduce surges in the circuit.

3. In combination a rectifying device hav-v ing a thermionic rectifying valve, a smoothing condenser for the rectified impulses, and a condenser in series with the filament circuit of the said rectifying valve, and an impedance in circuit with the condenser.

4. A rectifier system comprising a tube having filament and plate electrodes, the filament being adapted to be energized by a given voltage, means for connecting the filament to a source of current supply having a voltage higher than that for which the fi1a ment is adapted, and a condenser connected in series with said filament across the input terminals of said rectifier system, for reducing the voltage of the supply current to the valge for which the filament is adapted to be use r 5. An alternating current rectifier comprising a thermionic valve having filament and plate electrodes, means for connecting the filament to a source of alternating current power supply, a condenser connected in series with said filament to reduce the potential of the'current supplied to the filament to a voltage for which the filament is adapted,

"the plate supply circuit of the rectifier being connected across the terminals of said condenser.

In testimony whereof we afiix our signatures.

' PHILIP RAY COURSEY.

HUMFREY ANDREVVES. 

